Abstract:
Among the mimosoid legumes, few species exhibit the
systematic complexity of Acacia farnesiana (L.) Willd.
This widespread assemblage of species or microspecies is
probably native to the Americas [1-3] and has subsequently
been introduced into other tropical and subtropical
regions throughout the world. In the Americas,
Acaciafarnesiana (sensu lato) is found from the southern
U.S. to Argentina. Plants are often irregular in form but
are sometimes spreading and flat-topped [4, 5]. It is
often distinguished only with difficulty from species such
as A. tortuosa and A. macracantha [1,6] and in Africa
shows affinities toward A. sieberiana [1]. Several taxa
have been segregated from the Acaciafarnesiana species
complex. A. smallii is widely distributed in the southern
U.S. and northern Mexico [7]. A. pinetorum, another
north American segregate, occurs in S. Florida [7].
Acacia caven is an extra tropical South American taxon
with close affinities to A. farnesiana. Acacia farnesiana
(based on Mexican)Ilaterial which was not A. smallii) is a
tetraploid (2n = 52). A. caven is a diploid (2n = 26).
Apparently neither A. smallii or A. pinetorum have been
examined cytologically [7].
Vassal [3] subdivided the subgenus Acacia section
Acacia into two subsections Pluriseriae and Uniseriae
based largely on fruit morphology. Acaciafarnesiana and
its relatives are members of the Pluriserieae. Only one
cyanogenic member of the Pluriserieae has previously
been investigated. A. giraffae, a common African savanna
species, is known to contain proacacipetalin as the major
cyanogen [8].
Acacia farnesiana has been reported to be both cyanogenic
[9, 10] and acyanogenic [11]. Recent investigations
have suggested that the cyanogens are linamarin and
lotaustralin [8, 9, 12].
